The world turned upside down: the person in charge of prosecuting criminals has rushed to the defence of the panoply of human rights law that leads to a stream of villains heading out of the Old Bailey, wreathed in smiles, to carry on their lives of crime. Keir Starmer, director of public prosecutions, has objected to the idea of repealing the Human Rights Act 1998, denying it is a charter for criminals or "un-British".

This is a clear reference to Conservative policy on what Tory spokespeople always call "Labour's Human Rights Act" – at least, when they aren't laying the blame for it at the feet of "Europe". David Cameron would prefer a thoroughly British American-style bill of rights. The clauses of this important piece of Conservative legislation are not yet available. But it will be good, because Cameron has been thinking about it for at least three years.

He is not the first to have considered these matters. In medieval England there was a strong feeling that common law and the liberties it enshrined had become hidebound by arcane legal points and procedural niceties that let villains (mostly villeins) off the hook. The medieval answer was the star chamber which could bring speedy judgment to bear, particularly in cases of treason. It also had the advantage of putting the accused to torture. That speeded up justice no end.

We don't overtly do that sort of thing any more of course, so maybe we need something a little less rigorous than the Human Rights Act.

Perhaps something that emphasises our obligations to the state rather than just the outmoded rights and freedoms due from the state. That at least is the view of the Conservative liberty forum's 2006 essay, A British Bill of Rights & Obligations.

This gives some examples of obligations that might appear in such a document: respect for your parents, obeying "legitimate commands of the authorities", duty to work, observing moral requirements, strengthening national independence – presumably including not resorting to foreign bodies such as the European court of human rights (ECHR). When it comes to rights, judges would be able to look at people's claims "in context".

Fulfil your obligations and you might get your rights.

Unlike Cameron's putative bill the Human Rights Act is not a series of things the Labour government thought might be a good idea. It is an act: "to give further effect to rights and freedoms guaranteed under the European convention on human rights".

These are not new rights nor are they "Labour's". They were arrived at by the Council of Europe in 1950 in the aftermath of the second world war, informed by the realisation that even in advanced and democratic nations fundamental rights are fragile. They are the rights of individuals vis-a-vis the state, which had shown itself not to be a bastion of such freedoms. Britain, Cameron will be pleased to know, was a proud founder member of the council and enormously important in drawing up the convention. We signed it in 1950; we ratified it in 1951; we brought it into force in 1953.

Unfortunately we were a little late to the party when it came to enacting these rights in our own legislation.

Broadly the effect of the 1998 act was that citizens could access the provisions of the convention in Britain rather than having to go all the way to the ECHR in Strasbourg. So it's terribly pro-British, keeping legal work in Britain – British jobs for British judges – saving on air fares, hotel costs, interpreters.

Even if the act were repealed, that would not stop Strasbourg's foreign influence in the sovereign British nation state. Our signature on the document would stand and could not be expunged without some complex constitutional upheaval. Our word is our bond, in that terribly British phrase.

All that repeal would mean is that people in Britain would be faced with two almost inevitably contradictory documents as a source of our fundamental rights: Cameron's musings in the form of his bill of rights; and the real thing in the European convention. Indeed, paradox of paradox, the bill of rights would be subject to convention rights – convention compliant, in the legal jargon. It would be confusing; it would be inefficient; it would be expensive; and it would be just plain silly.